Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0720 DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	INSPECT VSS CONNECTOR FOR POOR CONNECTION Turn the ignition switch to the LOCK position. Disconnect the VSS connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Are the connector and terminals normal?	Yes	Go to the next step.
3		No	Repair or replace the connector and/or terminal, then go to Step 10.
4	INSPECT VSS POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT Turn the ignition switch to the ON position (engine off). Inspect the voltage at VSS connector terminal B. Is the terminal voltage B+ ?	Yes	Go to the next step.
4		No	Repair or replace the wiring harness, then go to Step 10.
5	INSPECT VSS GROUND CIRCUIT FOR OPEN CIRCUIT Turn the ignition switch to the LOCK position. Inspect for continuity between the VSS (wiring harness-side) terminal C and body ground. Is there continuity?	Yes	Go to the next step.
5		No	Repair or replace the wiring harness, then go to Step 10.
6	INSPECT TCM CONNECTOR FOR POOR CONNECTION Disconnect the TCM connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Are the connector and terminals normal?	Yes	Go to the next step.
6		No	Repair or replace the connector and/or terminal, then go to Step 10.
7	INSPECT VSS SIGNAL CIRCUIT FOR OPEN CIRCUIT Inspect for continuity between the VSS (wiring harness-side) terminal A and TCM (wiring harness-side) terminal 2K. Is there continuity?	Yes	Go to the next step.
7		No	Repair or replace the wiring harness, then go to Step 10.
8	INSPECT VSS SIGNAL CIRCUIT FOR SHORT TO GROUND Inspect for continuity between the VSS (wiring harness-side) terminal A and body ground. Is there continuity?	Yes	Go to the next step.
8		No	Repair or replace the wiring harness, then go to Step 10.
9	INSPECT VSS Inspect the VSS. (See VEHICLE SPEED SENSOR (VSS) INSPECTION .) Is the VSS normal?	Yes	Go to the next step.
9		No	Replace the VSS, then go to the next step. (See VEHICLE SPEED SENSOR (VSS) REMOVAL/INSTALLATION .)
10	VERIFY TROUBLESHOOTING OF DTC P0720 COMPLETED Make sure to reconnect all disconnected connectors. Clear the DTC from the TCM memory using the WDS or equivalent. Drive the vehicle with vehicle speed of 5 km/h {3 mph} or less and turbine speed of 2,000 rpm or more for 3.5 s or more Is the same DTC present?	Yes	Replace the TCM, then go to the next step. (See TCM REMOVAL/INSTALLATION .)
10		No	Go to the next step.
11	VERIFY AFTER REPAIR PROCEDURE Perform the "After Repair Procedure". (See AFTER REPAIR PROCEDURE .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE .)
11		No	DTC troubleshooting completed.